Maria Sharapova has only lost one set a the Australian Open 2015. (Getty Images)

It is Day 11 at the Australian Open, and there are a few surprises in both the men's and women's semifinals. Viewers can watch online the matches via live stream - free for subscribers - below.

According to Nick McCarvel of USA Today Sports, an American will be in the final in this event for the first time in five years. Tennis veteran and world rank No. 1 Serena Williams will face off against 19-year-old Madison Keys, who is world rank No. 35.

"It definitely feels amazing," Keys, an Illinois native, said after beating Venus Williams in a three-set quarterfinal. "It's one of those things where you want to feel this way all the time."

McCarvel reported that with the exception of Kim Clijsters, no one has beaten the Williams sisters back-to-back in a major since the 2009 U.S. Open. As a matter of fact, Keys has never played with Serena on the tennis court.

"It's just one of those things where I have to go out, and I have to do my best and really just have to stay focused on my side of the court, because she's obviously very, very good," Keys said. "So if I get too focused on what she's doing I think I can kind of let the moment get away from me."

USA Today reported that Keys' coach is former world No. 1 Lindsay Davenport. Serena was asked whether or not Davenport knew how to beat her.

"I'm sure she does," Serena said. "I would hope so."

Serena will be asking her older sister, Venus, on how to take Keys out.

"Oh, for sure I'll ask," the world No. 1 said to USA Today, then adding about Keys: "She's playing great. I told her I was really happy that she did well. It's good to see another American, another African-American, in the semifinals playing so well. Regardless, there's going to be an American in the finals, so that is great."

Before the matchup between Keys and Serena, Russian players Maria Sharapova and Ekaterina Makarova will take to the tennis court first. According to another USA Today article, world No. 2 Sharapova has never lost in five meetings with Marakova.

"I'm facing an opponent that wasn't necessarily a favorite coming into this stage," Sharapova, who has won five majors in her career, said. "That's always a tricky situation because she's going to come into the match free and almost happy to be in (the semifinals), and that's dangerous."

USA Today reported that Sharapova is just 9-9 in 18 major semifinals. In addition, 26-year-old Marakova has made it into her second Grand Slam semifinal back-to-back; her first one was at the US Open back in September.

As for the men's semifinals, Novak Djokovic of Serbia will face off against defending champion Stan Wawrinka of Switzerland. Merlissa Lawrence Corbett of Bleacher Report elaborated on the last time they played tennis, which was last year.

"It was an epic, four-hour battle," Corbett wrote. "The fifth set took 80 minutes and included a rain delay. After trading spectacular winners, Djokovic made two inexplicable unforced errors late in the match. Wawrinka took advantage and closed out the match."

Corbett added that Warwinka went on to win his first Grand Slam and has been a fixture in the top four since then. However, both men face pressure to perform.

"This will be the biggest X-factor in this match," Corbett wrote. "A wild-swinging, chip-on-the-shoulder Wawrinka is a dangerous dude. Similarly, Djokovic in world-beater mode is unbeatable."

The other men's semifinal matchup will be between Andy Murray of Great Britain and Tomas Berdych of the Czech Republic. According to USA Today, they will meet for the 11th time.

USA Today reported that Vallverdu used to be Murray's coach; however, he and Murray are still close friends. Despite that, the focus will be on how Murray will try to reach his fourth Australian Open final.

"Berdych leads their head-to-head 6-4 and will be brimming with confidence following his straight-set upset of Rafael Nadal in the quarterfinals," McCarvel wrote. "Much has been made of what Vallverdu has brought to Berdych's game, and in particular what game plan he'll craft when the Czech plays Murray."

The women's matches will start airing sequentially tonight at 9:30 p.m. ET, while the men's match between Murray and Berdych will air Thursday at 3:30 a.m. ET; all matches will be broadcasted on ESPN 2. While a subscription and login is required, online viewers can watch all games on WatchESPN.com or through the WatchESPN app for various devices.